Sinn Fein is favourite to top the poll following European elections in Northern Ireland despite Gerry Adams' arrest, an expert commentator has said.

The Sinn Fein president (65) was released from Antrim police station a week ago after four days of questioning by detectives about the 1972 murder of Belfast mother-of-10 Jean McConville and other alleged links with the IRA. He later claimed his arrest galvanised republicans' European election campaign.

Politics professor Richard Wilford from Queen's University said: "There is no doubt that Sinn Fein will hold the seat in the north and probably top the poll. The results won't demonstrate any growth because the Sinn Fein vote has plateaued."

Polls yesterday suggested Sinn Fein could take three of the Republic's 11 seats in the European Parliament.

Prof Wilford added: "I don't think you should construe the improved performance in any way being directly correlated with the arrest of Gerry Adams. The electorate north and south are very different and for the southern electorate it is a plague on all the houses of the other major parties because of austerity."

In the last European election in 2009, Sinn Fein's Bairbre de Brun topped the poll with 126,184 votes, but unionists took the two other seats.